Because of the new FCC rules, new TP-Link models would require a special method to install third party firmwares like LibreMesh. On TP-Link devices, you can typically identify that your router is FCC locked if you get a 18005 and/or Invalid Filename error when trying to flash. These instructions can help bypass these new restrictions.
Install dd-wrt: Select your router from dd-wrt.com. Download US version, factory-to-ddwrt-us.bin, if applicable.
Rollback to factory firmware: Follow instructions below to download correct file. You will have to set a username and password before continuing to dd-wrt’s Administration Page and selecting Upgrade Firmware. It does not matter if you choose to reset configuration after reset.
Official reverts: Go to the official dd-wrt page for your router. For example, WDR4300. Download the webrevert.rar package. Don’t forget to decompress.
Install LibreMesh: Download factory version of LibreMesh, not sysupgrade. You must rename the file to the name of one of the official TP-Link firmware files (e.g. wdr3500v1_en_us_3_14_3_up_boot(151104).bin or wdr4300v1_en_3_14_3_up_boot(150518).bin). If you are unsure of the name for your device, try searching the OpenWRT page for your device and searching the page for some variation of the filenames above.